Sorry. I forgot about those buffers. Yes. They are needed to avoid damage to the pads of PERST, WAKE and CLKREQ lines in case if there happen to be multiple active drivers. in AGX <-> AGX case, there are brief time periods when this (multiple drivers being active) happens. So, to avoid pad damage/reliability issues in the long run, you need to have a cable with this buffer or an equivalent circuit to accomplish the electrical isolation.